Correlation between proteoglycan and alveolar bone resorption in a mouse periodontitis model

Abstract

Objective To analyze changes in proteoglycan and its correlation with alveolar bone resorption in periodontitis. Methods Twelve eight-week-old C57BL/6J male mice were selected, and the periodontitis model was established by ligating the right maxillary second molar with 6-0 silk thread. The nonligated part of the left maxilla was used as the control. The mice were killed 14 days after the operation. Micro-CT was used to assess alveolar bone resorption. HE staining was used to observe the alveolar bone profile, and TRAP staining was conducted to examine the positive rate of osteoclasts. The expression of proteoglycan-related genes, such as aggrecan (ACAN), biglycan (BGN), versican (VCAN), decorin (DCN), osteoclast-related genes, such as cathepsin K (CTSK), matrix metalloprotein-9 (MMP-9), and receptor activator of nuclear factor kappa-B ligand (RANKL), and inflammation-related genes, such as interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), was detected by real-time quantitative PCR. Additionally, the correlation of the expression of proteoglycans with osteoclast-related genes and inflammation-related genes was evaluated by Pearson correlation analysis. Results The resorption of alveolar bone on the periodontitis side increased. TRAP staining showed that the number of osteoclasts was substantially increased in the maxilla with periodontitis. Real-time quantitative PCR demonstrated that compared with the control side, the expression of proteoglycan-related genes, such as ACAN, BGN, and DCN, was decreased, whereas the expression of the VCAN gene was significantly increased in the periodontitis side. Meanwhile, the expression of osteoclast-related genes, such as CTSK, MMP-9, and RANKL, and inflammation-related genes, such as IL-1β, IL-6, and TNF-α, was markedly increased in the periodontitis side (P<0.05). Pearson correlation analysis indicated a negative correlation between the expression of proteoglycans and the mRNA levels of osteoclast-related genes and inflammation-related genes (P<0.05). Conclusion The expression of proteoglycan was closely related to alveolar bone resorption in a periodontitis model.

Keywords

• periodontitis
• periodontal tissue
• extracellular matrix protein
• proteoglycan
• glycosylation
• osteoclasts
• inflammation
• alveolar bone resorption